http://www.ck12.org Chapter 17. Circuits
- The equivalent resistance of resistors in parallel is
1
Requivalent=
1
R 1 +1
R 2 +...- In a series circuit all resistors have the same current and in a parallel circuit all resistors have the same potential
drop. - For any electric circuit the electric powerPis the product of currentIand voltageV
P=IV
- Joule heating is the heat dissipated through a resistor. It is equal to the rate at which energy flows through the
resistor.
P=IV→P=I^2 R
P=IV→P=
V^2
R
- Kirchhoff’s laws are two statements useful in analyzing circuits.
- The sum of the currents entering any junction must equal the sum of the currents leaving any junction.
- The sum of the potential changes around any closed circuit loop must equal zero.
The first is a statement of charge conservation and the second is a statement of the conservation of energy.
The first is a statement of charge conservation and the second is a statement of the conservation of energy.
- Ammeters are devices that measure the currents within a circuit. They are placed in series with a component in
order to measure the current passing through it and have small resistances. - Voltmeters are devices that measure the voltages in a circuit. They must be placed in parallel with a component
in order to measure the voltage drop across it and have large resistances.